TreeView页面刷新后出现问题

树型支点，第一次打开页面时是正常的，但再刷新后就打不开支点了，就像上图那样，请问怎样解决。



<%@ Page Language="C#" AutoEventWireup="true" CodeFile="menuAction.aspx.cs" Inherits="menuAction" %>



<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">

<html>

<head runat="server">

    <title>123</title>

</head>

<body>

    <form id="form1" runat="server">

        <asp:TreeView ID="TreeView1" runat="server" ExpandDepth="0" ImageSet="Arrows">

            <Nodes>

                <asp:TreeNode Text="销售" Value="销售" SelectAction="Expand">

                    <asp:TreeNode Text="现付" Value="现付"></asp:TreeNode>

                    <asp:TreeNode Text="计划" Value="计划"></asp:TreeNode>

                    <asp:TreeNode Text="出货" Value="出货"></asp:TreeNode>

                </asp:TreeNode>

            </Nodes>

            <ParentNodeStyle Font-Bold="False" />

            <HoverNodeStyle Font-Underline="True" ForeColor="#5555DD" />

            <SelectedNodeStyle Font-Underline="True" ForeColor="#5555DD" HorizontalPadding="0px"

                VerticalPadding="0px" />

            <NodeStyle Font-Names="Tahoma" Font-Size="10pt" ForeColor="Black" HorizontalPadding="5px"

                NodeSpacing="0px" VerticalPadding="0px" />

        </asp:TreeView>

    </form>

</body>

</html>



using System;

using System.Data;

using System.Configuration;

using System.Collections;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;



public partial class menuAction : System.Web.UI.Page

{

    OleBaseClass bc = new OleBaseClass();

    protected void Page_Load(object sender, EventArgs e)

    {



        if (Convert.ToString(Session["userid"]) == "")

        {

            Response.Write("<script>parent.location.href='default.aspx';</script>");



        }

        if (!IsPostBack)

        {



        }

    }





}

--------------------编程问答-------------------- 那就在if (!IsPostBack)里写上TreeView1.expand=true;
--------------------编程问答-------------------- TreeView1.ExpandAll();

加上后是全部都打开了，但还是提示脚本出错，

补充：.NET技术 ,  ASP.NET